Anatomy and realism is important. Anime and lolicon art is very stylized, yes, but you can draw well stylisticly without a FOUNDATION of proper anatomy and realism to go off from. That's why deviantart horrors look so bad...they don't start from anatomy, they start from "anime style"...thus the pictures are flat, without perspective, and monstrous looking.

Also, Practice. Find some child model pictures: you can get some good sets and magazines on http://www.akiba-online.com to work from.

When you draw, think about what you're drawing IN SPACE...think about the PHYSICALITY, the actual heft and weight and matter of the object itself. Truly good art isn't just lines on a piece of paper...it feels vivid, and real.